I've been here a long time, but never post. Just thought I would on this point as it seemed to be us you were referring to.
We used to go to Infinity Foods for our wholesale products. They are very local to us, so I'm unsure of their delivery costs / distances.
http://www.infinityfoodswholesale.co.uk/With regard to products, we concentrated on selling goods that weren't readily available to consumers on supermarket shelves. It was only a couple of years ago, but most of them are now available at good prices in supermarkets, without postage costs to customers.
Focusing energy on sales of 'green' consumables to local businesses is working better for
our business. But it may work for you. You'd have to find the things people want, but can't get easily, which is the crux of any online sales business I suppose.
Anyway... I'll go back to being quiet again now!